Spot-welding pliers



Dec. 23, 1941.

A. A. CAMPBELL, JR

SPOT-WELDING PLIERS Filed Feb. l, 1940 Patented Dec. 23, 1941 UNITED STATES PATENT OFFICE SPOT-WELDING PLIERS Arthur A. Campbell, Jr., Madison, Wis. Application February 1, 1940, Serial No. 316,814

2 Claims.

This invention relates to an electrical welding tool and more particularly this invention relates to a portable electric spot-welding tool.

One object of this invention is to provide a portabl spot-welding tool which may be easily and readily carried about without the necessity of moving heavy and cumbersome equipment.

Another object of this invention is to provide a portable spot-welding tool which is easily operated and is very efiicient in operation.

Another object of this invention is to provide a portable-welding tool which due to its unique construction and the fact that it is provided with removable electrode carrying jaws of different shapes, may be used to weld metal in otherwise inaccessible places.

A further object of this invention is to provide such a tool having a switch to control the heavy current through the electrodes, the switch operating only when the electrodes have come to rest in welding position thereby eliminatin excessive arcing,

A still further object of this invention is the provision of adequate insulation between each of the parts to insure protection from dangerous shocks to the user of the tool.

Other and further objects of this invention will become readily apparent as the following description of preferred and practical embodiments of the invention proceeds. In the drawing which accompanies and forms a part of this specification and in which like reference numerals refer to like parts throughout:

Figure 1 is an elevational View of'one form of an electric spot-welding tool constructed in accordance with the concepts of 'the present invention;

Figure 2 isa longitudinal section through the tool; the jaws being moved to: welding position;

Figure 3 is atra'nsverse section takenon; line 3-3 of Figure 1; w u

Figure 4 is a perspective 'viewof another type of removable jaw;

Figure 5 is a perspective view of a differently shaped jaw.

Referring now to the drawing in detail, the spot-welding tool is shown in the form of pliers having a fixed jaw I and a movable jaw 2. The fixed jaw is rigidlysecured to a head 3, and, integral with the jaw l and extending rearwardly from the head 3 is an insulated fixed handle 4. The head 3 consists of two plates 5 and 6, one on either side of the jaws and separated from the jaws by sheets of insulating material I and 8.

Insulated screws 9 secure the plates 5 and 6 of the head 3 to the fixed jaw and insulated handle I and 4, respectively.

The movable jaw 2 is pivoted to the head as at l0 and terminates at its rearward end in an arcuate toothed segment II. An insulated movabl handle 12 is pivoted to the head as at l3 and at its forward end carries an arcuate toothed segment l4 meshing with the toothed segment I Due to this construction, movement of the movable handle l2 toward the fixed handle 4 causes the jaws to approach one another. Each of the jaws is provided with a cutout portion l5 forming a stepped joint to receive a current conducting'section l6 to which is removably secured an electrode I! by means of screw l8. The two sections of the jaw are separated by a strip of electrical insulating material. The sections l6 of the jaws are secured to the main portion of the jaws by the bolt I 9, and are readily removable so that sections of various shapes may be used for welding material having obstructions which would otherwise prevent the electrodes contacting the metal to be welded. A conducting section of a jaw having a yoke 20 to permit welding in back of an obstruction is shown in Figure 4, while a similar conducting section having the electrode ofiset to facilitate welding within a narrow space is shown in Figure 5. Obviously these interchangeable conducting sections may be made in various shapes and sizes to weld diflerently shaped sections ing from the secondary 23 of a transformer. 24,

the primary 25 of the transformer being con nected to any suitable'source of' electrical. current. It is, of courseQapparent tothose skilled "in the art to' which this inventionpertains, that the electrodes and/or conducting se'ctionslmay be made water cooled." This also helps to prevent excessive burning of the electrodes.

In electrical spot-welding it is highly desirable that the electrodes shall be in firm contact with the metal which is to be welded, before the current is sent through the electrodes in order to prevent arcing and consequent burning of the electrodes. To accomplish this the head plates 5 and 6 are provided with arcuate slots 26 and 21 to receive the pivot pins l3 of the movable handle I2. Springs 28 are placed in the slots and held in position upon studs 29 at the bottom of the slots and studs 30 on the pivot pins l3. The Springs 28 are of sufficient strength to hold the pivot pins against the top wardly a plate 33 hinged to the switch box 34 carried by the fixed handle 4. Movement of the plate 33 causes a plunger 35 to move inwardly against the action of a spring 33. Mountedupon the plunger 35 so as to have pivotal movement in one direction is a dog 31. As the plunger moves inwardly the dog 31 strikes a resilient metal contact 38 and moves it downward against a substantially rigid member 39 electrically connected to one side of a relay. When the contact 38 strikes the member 39 the outer end of the contact 38 bends downwardly allowing the dog 31 to pass by it and thus break the circuit. Actuation of this switch energizes a relay 48 which draws up its armature and closes the circuit to the electrodes. This relay may be connected to anysuitable electrical outlet or may be connected to a third coil on the transformer 25. In this way a relatively weak current may be run through the switch and thereby eliminate the danger of electrical shock to the operator. As a further safeguard the handles 4 and I2 are covered with electrical insulation'of some type, and all of the various pins, bolts, pivots and parts have incourse, will'prevent excessive burning of the electrodes. When pressure on the handles is released a spring 4| will return them to their open position. Due to the pivotal connection of the dog 31 to the plunger 35, ,the dog'will swing back when it strikes the contact 38 on its upward stroke and will not move the contact.

It will be readily understood by those skilled in the art to which this invention pertains that the showing of the device is very diagrammatic and that the invention is capable of many refinements, for example, the wiring of the elec trical circuits and the form and shape of the' spot-welding tool may take different forms than that shown and described herein. Also the mechanism shown and described herein to move the jaws l and 2 toward and away from each other might well be changed to use a system of cams or levers, etc., and further, if so desired, both jaws may be made movable. Further, the jaws and electrodes of the device of this invention may be constructed so as to provide water cooling for them. This could be done in various ways as is well known to those skilled in the art to which this invention pertains, and would be a relatively simple matter, its chief advantage would be to help prevent excessive burning away of the electrodes due to the large amount of heat generated when a spot weld is made. The particular form of switch 34 shown and described in detail moreover, is not essential as it is obvious that many other types and forms of switch to accomplish the same result could be used without departing from the spirit of the invention. Various other and further modifications can well be made without departing from the spirit of my invention and the scope of the appended claims.

What I claim is:

1. A portable electric spot-welding tool comprising, a head, a jaw and a handle rigidly fixed to and insulated from said head,a movable jaw pivotally connected to said head and having an arcuate toothed inner end, a movable handle carried by said head by means of a yielding pivotal connection in slots in said head, said mov-,

able handle having an arcuate toothed outer end to mesh with the teeth on the inner end of said movable jaw, and means to close a circuit through electrodes carried by said jaws after said electrodes have been brought into firm contact with the material to be welded.

2. An electric spot welding tool comprising: a head consisting of two plates having arcuate slots therein; a fixed jaw and handle rigidly secured to, and insulated from, said head; a movable jaw pivotally connected to, and insulated from, said head, said movable jaw having an arcuate toothed segment on its inner end; a movable handle pivotally connected to, and insulated from, said head, said movable handle having an arcuate toothed segment-meshing with v the toothed segment on said movable jaw; a curhandle; and a switch carried by said fixed handle and adapted to be actuated by the movement of said movable handle to allow a momentary surge of current to pass between said electrodes after said electrodes are firmly in contact with the material to be welded; all substantially as described.

ARTHUR A. CAMPBELL, JR. 

